Uroptychus squamifer, Baba, 2018

Baba, Keiji, 2018, Chirostylidae of the Western and Central Pacific: Uroptychus and a new genus (Crustacea: Decapoda: Anomura), Tropical Deep-Sea Benthos (Mémoires du Muséum national d'Histoire naturelle 212), pp. 1-612: 499-502

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Uroptychus squamifer

n. sp.

Uroptychus squamifer   n. sp.

Figures 250 View FIGURE 250 , 251 View FIGURE 251

TYPE MATERIAL — Holotype: New Caledonia, South of Loyalty Ridge. BATHUS 3 Stn DW 778, 24°43’S, 170°07’E, 750- 760 m, 24.XI.1993, ov. ♀ 9.4 mm ( MNHN-IU-2014-16967). GoogleMaps  

ETYMOLOGY„ From the Latin squamus (scale) and fer (the suffix meaning bear), referring to scale-like ridges on the carapace dorsal surface.

DISTRIBUTION„ South of Loyalty Ridge; 750- 760 m.

DESCRIPTION„ Carapace: About as long as broad; greatest breadth 1.7 × distance between anterolateral spines. Dorsal surface slightly convex from anterior to posterior, with weak depression between anterior and posterior branchial regions, and between anterior and posterior branchial regions, covered with setiferous, scale-like, granulate ridges; 2 epigastric spines preceded by depressed rostrum, flanking larger spine placed slightly posteriorly. Lateral margins convexly divergent posteriorly, ridged along posterior quarter, with 10 spines discernible in dorsal view; first 3 spines ventral to level of remaining spines; first anterolateral, well developed, directed forward, overreaching much smaller lateral orbital spine; second and third small, placed on hepatic margin; fourth to sixth on anterior branchial margin and seventh to tenth on posterior branchial margin; fourth slightly smaller than first, fifth and sixth small, seventh to ninth well developed, tenth last much smaller; extra small spine between ninth and tenth on left side, and another small spine between eighth and ninth on right side, last spine followed by ridge leading to posterior end. Rostrum somewhat deflected ventrally, narrow triangular, with interior angle of 20°; length half as long as remaining carapace, breadth much less than half carapace breadth at posterior carapace margin; lateral margin with 4 spinules; dorsal surface flattish, distinctly lowered from level of epigastric region. Lateral orbital spine slightly anterior to level of anterolateral spine, and separated by basal breadth of anterolateral spine. Pterygostomian flap feebly granulose on surface, anterior margin somewhat angular, produced to strong spine.

Sternum: Excavated sternum convexly produced anteriorly, surface with rounded ridge in midline. Sternal plastron 0.9 × as long as broad, lateral extremities moderately divergent posteriorly. Sternite 3 moderately depressed, anterior margin shallowly excavated, with 2 small submedian spines (with extra small spine lateral to left spine) separated by narrow notch. Sternite 4 with scattered denticulate ridges on surface; anterolateral margin slightly longer than posterolateral margin, denticulate, anteriorly with 2 processes (distally broken) placed side by side, mesial one smaller. Anterolateral margin of sternite 5 denticulate and convexly divergent posteriorly, slightly shorter than posterolateral margin of sternite 4.

Abdomen: Smooth. Somite 1 with well-developed setiferous transverse ridge. Somite 2 tergite 2.6 × broader than long; tergite with setiferous anterior transverse ridge, pleuron concavely divergent posteriorly, anterolateral and posterolateral termini angular. Pleuron of somite 3 tapering to sharp tip. Telson half as long as broad; posterior plate 1.5 × longer than anterior plate, distinctly emarginate on posterior margin.

Eye: Short relative to length, 1.5 × longer than broad, feebly narrowed proximally, barely reaching midlength of rostrum. Cornea slightly dilated, about as long as remaining eyestalk.

Antennule and antenna: Ultimate article of antennule 3.7 × as long as high. Antennal peduncle overreaching eye by full length of article 5. Article 2 with well-developed lateral spine. Antennal scale slightly falling short of distal end of

peduncle, 2 × broader than article 5. Articles 4 and 5 each with distomesial spine; article 5 1.8 × longer than article 4, breadth 0.5 × height of antennular ultimate article. Flagella broken.

Mxp: Mxp1 with bases close to each other. Mxp3 basis with 4 denticles on mesial ridge, distal one distinct, others obsolescent. Ischium with very small denticles (about 35) on crista dentata, flexor margin not rounded distally. Merus twice as long as ischium, ridged along flexor margin with a few obsolescent denticles distal to midlength, distolateral spine well developed. Carpus with 1 distolateral and 1 proximo-lateral spine, and a few denticles between.

P 1: Missing.

P 2-4: Relatively slender, with very sparse, relatively short setae. Meri moderately compressed mesio-laterally, successively shorter posteriorly ( P 3 merus 0.9 × length of P 2 merus, P 4 merus‰.9 × length of P 4 merus), equally broad on P 2-4; lengthbreadth ratio, 7.0 on P 2, 5.9 on P 3, 4.7 on P 4; dorsal margin with row of spines of irregular sizes (13-14 spines on P 2 and P 3, 9 spines on P 4); ventrolateral margin with 9 spines on P 2 and P 3, 7 spines on P 4; ventromesial margin with 6 or 7 small spines on P 2 only; lateral surface sparsely denticulate. P 2 merus as long as carapace, 1.3 × longer than P 2 propodus; P 3 merus 1.1 × longer than P 3 propodus; P 4 merus 0.9 × length of P 4 propodus. Carpi subequal in length on P 2-4; much longer than dactyli (carpus-dactylus length ratio, 1.9 on P 2, 1.8 on P 3, 1.5 on P 4); extensor margin with row of spines (9 on P 2, 8 on P 3 and P 4), with subparalleling row of 6-7 smaller spines laterally; carpus-propodus length ratio, 0.6 on P 2 and P 3, 0.5 on P 4. Propodi successively longer posteriorly; extensor margin with a few small proximal spines (3 on P 2, 2 on P 3, 4 on P 4); flexor margin nearly straight, with pair of terminal spines preceded by 7 slender movable spines on P 2 and P 3, 6 spines on P 4, proximalmost spine remote from proximal second, situated at proximal third on P 2 and P 3, at midlength on P 4. Dactyli successively longer posteriorly, length 0.5 × that of carpi on P 2, 0.6 × on P 3, 0.7 × on P 4; onethird length of propodi on P 2-4; flexor margin slightly curving, with 13 or 14 sharp spines perpendicular to margin and proximally diminishing, ultimate spine slightly longer than penultimate.

Eggs. Number of eggs carried, 8 (normal number probably more); size, 1.23 mm × 1.23 mm- 1.40 mm × 1.19 mm.

REMARKS„ Uroptychus squamifer   resembles U. strigosus   n. sp. in the carapace that bears scale-like ridges on the dorsal surface and a row of strong spines on the lateral margin, and in the abdominal somite 1 that bears a sharp transverse ridge. However, they differ from each other in many aspects as discussed under the remarks of U. strigosus   (see below).